My DD only got rid of hers recently at age 3.5!! ::O:, but we used the dummy fairy line too. I hadn't pushed it earlier as she's a bit fragile and she was taking her time getting used to DS.

I got her a little gift bag and we collected all the dummies from around the house (there were lots she took em everywhere) and put it out for the fairy to take to the sick babies in hospital becasue they needed them more than DD.
We had talked about it a few days prior so she knew what would happen. I suggested that the fairy 'might' leave her a gift to say thanks, and she said she thought the fairy might leave her a turtle! Great says Mum....aggghh! Where was I going to get one of those. Thank goodness for the littlest petshop...so she got her turtle.
Then a couple of nights later I left her another present and a little note that said thanks from the sick babies - cos she really had done well - she was obsessive with them.